This invention relates to a remote copy storage device system, a center computer and a remote copy method each of which is used for storing the same information as information stored in a center storage device to a plurality of remote storage devices.
Computers and their networks have now become indispensable infrastructures to support economical activities of human being. When any fault occurs in the computer as the infrastructure, therefore, great influences are exerted not only on the economic activities of companies but also on the social lives of ordinary people. Among the faults of the computers, the loss of data stored in storage devices is the most serious and critical of all. Hardware and software constituting the computer can be replaced by normal ones when any fault occurs in them but the data stored in the storage devices cannot be recovered once lost.
Therefore, to prevent the loss of data stored in the storage devices owing to a large-scale disaster such as an earthquake, a remote copy technology that installs storage devices at two sites spaced apart from each other and allows the storage devices to mutually duplicate and store the data between them at two sites has been put into practical application. Market needs of the storage devices call for a remote copy technology capable of further increasing the installation sites of the storage devices to three or more sites.
For example, US2003/0051111 A1 discloses a remote copy technology capable of always duplicating the data after the sequence of updating of data is secured among storage devices installed at three or more sites. According to this remote copy technology, even when a fault occurs in a certain storage device and the data is lost from the storage device owing to an accident, the data can be reconstituted with guaranteed sequence on the basis of the data stored in two or more other storage devices.